Thermal interface for riding heatsink

ABSTRACT

A pluggable optical module may include a substrate. The pluggable optical module may include a compressible sliding thermal interface disposed on the substrate to contact a riding heatsink. The compressible sliding thermal interface material may be compressed to fill interstices between a first surface of the substrate and a second surface of the riding heatsink. The compressible sliding thermal interface may protrude from the first surface of the substrate such that insertion of the pluggable optical module into a cage compresses the compressible sliding thermal interface to achieve a threshold thermal boundary resistance.

RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application No. 62/627,544, filed on Feb. 7, 2018,the content of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The present disclosure relates to thermal interfaces. More particularly,some aspects of the present disclosure relate to a compressible slidingthermal interface for a riding heatsink disposed in proximity to and/orcontacting a pluggable optical module.

BACKGROUND

Pluggable optical modules, such as pluggable transceivers, may includemultiple internal components to enable high-speed communications in anoptical communications system. For example, a pluggable optical modulemay include a digital signal processor (DSP), a transmitter opticalsubassembly (TOSA), a receiver optical subassembly (ROSA), atransmitter/receiver optical subassembly (TROSA), electronics associatedtherewith, and/or the like. A housing of a pluggable optical module maybe coupled to a riding heatsink of a cage to provide heat-dissipationcapacity for the pluggable optical module. The pluggable optical modulemay be plugged into the cage, which couples the pluggable optical moduleto the riding heatsink. The cage may contain increasing quantities ofpluggable optical modules to achieve increasing bandwidth for opticalcommunications. With increasing quantities of high-speed components andwith increasing miniaturization of pluggable optical modules andelectro-optical components disposed therein to enable a greater densityof pluggable optical modules in a single cage, improvingheat-dissipation performance is desirable.

SUMMARY

According to some possible implementations, a device may include apluggable optical module. The pluggable optical module may include asubstrate. The pluggable optical module may include a compressiblesliding thermal interface material disposed on the substrate, whereinthe compressible sliding thermal interface material is compressed by athreshold clamping force to fill interstices between a first surface ofthe substrate and a second surface of a riding heatsink, and wherein thecompressible sliding thermal interface protrudes from the first surfaceof the substrate such that insertion of the pluggable optical moduleinto a cage that includes the riding heatsink compresses thecompressible sliding thermal interface by the threshold clamping forceto achieve a threshold thermal boundary resistance.

According to some possible implementations, a pluggable optical modulemay include a substrate. The pluggable optical module may include acompressible sliding thermal interface disposed on the substrate tocontact a riding heatsink, wherein the compressible sliding thermalinterface material is compressed to fill interstices between a firstsurface of the substrate and a second surface of the riding heatsink,and wherein the compressible sliding thermal interface protrudes fromthe first surface of the substrate such that insertion of the pluggableoptical module into a cage compresses the compressible sliding thermalinterface to achieve a threshold thermal boundary resistance between thepluggable optical module and the riding heatsink.

According to some possible implementations, an electro-optic transceivermay include a substrate for inserting into a cage. The electro-optictransceiver may include an interface material disposed on the substrate,wherein the interface material is compressible to enable insertion ofthe substrate into the cage, wherein the interface material extendsabove a surface of the substrate, and wherein the interface material isthermally conductive and is associated with a threshold thermal boundaryresistance at a threshold clamping force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams of an overview of an example implementationdescribed herein.

FIGS. 2A-2D are diagrams of an example implementation described herein.

FIG. 3 is a flow chart of an example process for using a pluggableoptical module with a compressible sliding thermal interface.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements.

A riding heatsink may be clamped to a housing of a pluggable opticalmodule to enable the riding heatsink to improve a heat dissipationcapacity of the pluggable optical module. However, insufficient amountsof clamping force applied by a cage to the pluggable optical module whenthe pluggable optical module is inserted into the cage may result in theriding heatsink failing to achieve a threshold level of heat dissipationcapacity for the pluggable optical module. Further, respective surfacesof the riding heatsink and the pluggable optical module may berelatively rough, which may result in air-filled interstices between thehousing of the pluggable optical module and the riding heatsink whenthere is a metal-on-metal contact between the respective surfaces of theriding heatsink and the pluggable optical module. For example, theair-filled interstices of the metal-on-metal contact may provide aninsulating barrier, thereby negatively impacting an achievable thermalboundary resistance.

Some implementations described herein enable increased clamping force bydisposing a compressible sliding thermal interface between the ridingheatsink and a housing of a pluggable optical module. For example, thecompressible sliding thermal interface may be disposed in a depressionof a substrate of the housing such that the compressible sliding thermalinterface protrudes above a surface of the housing. In this case, whenthe pluggable optical module is plugged into a cage, the compressiblesliding thermal interface increases a clamping force between the ridingheatsink and the housing of the pluggable optical module relative to ametal-on-metal contact between the riding heatsink and the housing ofthe pluggable optical module. Based on increasing the clamping force, athreshold level of clamping force may be achieved, which may achieve athreshold thermal boundary resistance, thereby improving heatdissipation capacity of the riding heatsink for the pluggable opticalmodule.

Moreover, based on compressing the compressible sliding thermalinterface, the compressible sliding thermal interface may fillinterstices between the housing and the riding heatsink (e.g., airgaps), thereby increasing thermal conductivity between the pluggableoptical module and the riding heatsink. Furthermore, based on using aslidable thermal interface material, the compressible sliding thermalinterface material may be relatively durable, thereby reducing anecessity of frequent replacements to the compressible sliding thermalinterface material relative to using a non-slidable thermal interfacematerial.

FIGS. 1A and 1B are diagrams of an overview of an example implementation100 described herein. As shown in FIG. 1A, example implementation 100may include a substrate 110 and a compressible sliding thermal interface120. In some implementations, substrate 110 may be a surface of apluggable optical module. For example, substrate 110 may be a housing ofthe pluggable optical module, which may include one or more electricalcomponents, optical components, electro-optical components, and/or thelike. In some implementations, the pluggable optical module may be apluggable transceiver. In some implementations, substrate 110 may be asurface of an active optical module, a passive optical module, and/orthe like. In some implementations, substrate 110 may be a surface of awavelength selective switch, an amplifier, a transmitter, a receiver, adigital signal processor, and/or the like. In some implementations,compressible sliding thermal interface 120 is applied (e.g., duringmanufacture) to substrate 110, and a riding heatsink is disposed (e.g.,as a result of assembly) onto compressible sliding thermal interface 120and substrate 110. In some implementations, compressible sliding thermalinterface 120 is applied to the riding heatsink, and compressiblesliding thermal interface 120 and the riding heatsink are disposed ontosubstrate 110. In this case, the riding heatsink may include adepression to receive compressible sliding thermal interface 120 ratherthan substrate 110.

As further shown in FIG. 1A, compressible sliding thermal interface 120may be disposed into a depression in substrate 110. For example,substrate 110 may include a depression with a depth 150 and a width 152.In some implementations, depth 150 may be approximately 500 micrometers(μm). In some implementations, depth 150 may be between approximately100 μm and 2000 μm. In some implementations, width 152 may beapproximately 20 millimeters (mm). In some implementations, width 152may be between approximately 5 mm and 50 mm.

In some implementations, a particular amount of compressible slidingthermal interface 120 may be disposed into the depression in substrate110, such that compressible sliding thermal interface 120 protrudesabove surface 112 of substrate 110 by height 154. In someimplementations, height 154 may be approximately 100 μm. In someimplementations, height 154 may be between approximately 0 μm and 100μm. In this way, based on compressible sliding thermal interface 120protruding above surface 112 by height 154, compressible sliding thermalinterface 120 is compressed with a threshold clamping force whensubstrate 110 (e.g., when a pluggable optical module including substrate110) is inserted into a cage. Moreover, based on height 154 being lessthan approximately 100 μm, compressible sliding thermal interface 120 isconfigured to not interfere with insertion of a pluggable optical moduleinto a cage. In some implementations, compressible sliding thermalinterface 120 may be a compliant material.

As shown in FIG. 1B, compressible sliding thermal interface 120 may bedefined by an outer surface 170 (e.g., a flexible interface structure)enclosing an inner body 172, which may be an interface filling material.In some implementations, compressible sliding thermal interface 120 maybe a fluid compressible sliding thermal interface 120. For example,inner body 172 may be a compressible, slidable, conductive fluid, andouter surface 170 may be an encapsulation material surrounding thecompressible, slidable, conductive fluid. In this case, inner body 172may be a conductive liquid and outer surface 170 may be a metalenclosure enclosing the conductive liquid. In some implementations,outer surface 170 may be a flexible support structure. For example,outer surface 170 may include one or more inner members forming acomposite structure of structural cells, inner supports, flexiblestructural compartments, and/or the like. Additionally, oralternatively, inner body 172 may be a conductive gas or plasma enclosedby outer surface 170.

In some implementations, outer surface 170 may be a surface of amaterial comprising inner body 172. For example, when inner body 172 isa viscous liquid, outer surface 170 may be a surface of the viscousliquid rather than a separate encapsulation material containing theviscous liquid. In some implementations, compressible sliding thermalinterface 120 may be a carbon nano-tube material or carbon fibermaterial. In some implementations, compressible sliding thermalinterface 120 may be a thermal grease. In this way, by encapsulating afluid material of inner body 172 inside a structure formed by outersurface 170, compressible sliding thermal interface 120 enablesinsertion of a pluggable optical module into a cage without portions ofcompressible sliding thermal interface 120 being dispersed or dislodged.

Although some implementations are described herein in terms of aninterface material disposed between a pluggable optical module and ariding heatsink, other implementations are possible. For example,compressible sliding thermal interface 120 may be disposed on asubstrate 110 of another type of pluggable electro-optic transceiver,and may be sandwiched between the pluggable electro-optic transceiverand another type of component to achieve less than a threshold thermalboundary resistance, as described herein. Similarly, compressiblesliding thermal interface 120 may be disposed on another portion of apluggable optical module, such as between a surface of the pluggableoptical module and a digital signal processor disposed in the pluggableoptical module.

As indicated above, FIGS. 1A and 1B are provided merely as one or moreexamples. Other examples may differ from what is described with regardto FIGS. 1A and 1B.

FIGS. 2A-2D are diagrams of an example implementation 200 describedherein.

As shown in FIG. 2A, example implementation 200 includes substrate 110with a cavity 202.

As shown in FIG. 2B, a compressible sliding thermal interface 120 may bedisposed into cavity 202 to fill cavity 202. In some implementations,substrate 110 may not include a cavity 202, and compressible slidingthermal interface 120 may be disposed onto a surface of substrate 110rather than in a cavity 202.

As shown in FIG. 2C, substrate 110 with compressible sliding thermalinterface 120 may be aligned to an opening 204 of cage 206, which mayinclude a riding heatsink 208 attached to a surface of cage 206. In someimplementations, cage 206 may include multiple openings 204 to receivemultiple pluggable electro-optic transceivers, such as substrate 110,and may include multiple riding heatsinks 208 to provide heatdissipation for the multiple pluggable electro-optic transceivers. Insome implementations, riding heatsinks 208 may be disposed on top ofcage 206. In some implementations, riding heatsinks 208 may be recessedinto a top of cage 206 and/or may form a top of cage 206 or a section ofthe top of cage 206.

As shown in FIG. 2D, substrate 110 and compressible sliding thermalinterface 120 are inserted into opening 204 of cage 206. Based onsubstrate 110 and compressible sliding thermal interface 120 beinginserted into opening 204 of cage 206, compressible sliding thermalinterface 120 may be compressed, which may increase a clamping force onsubstrate 110, and may reduce a thermal boundary resistance betweensubstrate 110 and riding heatsink 208, thereby improving heatdissipation performance. In some implementations, substrate 110 (and/oran electro-optic transceiver thereof) may contact (e.g., conformallycontact) riding heatsink 208. In some implementations, substrate 110 maybe within a threshold proximity of riding heatsink 208 with one or moreintermediate layers of material.

In some implementations, a threshold clamping force between substrate110 and riding heatsink 208 is increased by a presence of compressiblesliding thermal interface 120 relative to another configuration withoutcompressible sliding thermal interface 120. Based on achieving athreshold clamping force, compressible sliding thermal interface 120 mayfill interstices between substrate 110 and riding heatsink 208, therebyachieving a threshold thermal conductivity, a threshold thermal boundaryresistance, and/or the like. In some implementations, a fill factor forcompressible sliding thermal interface 120 when filling intersticesbetween substrate 110 and riding heatsink 208 is greater than athreshold percentage fill factor, thereby increasing a fill factorrelative to a bare surface-on-surface contact of rough surfaces ofsubstrate 110 and riding heatsink 208.

In some implementations, the threshold thermal conductivity is at leastapproximately 1000 Watts per meter Celsius (W/mC). In this way, based onimproving the thermal conductivity relative to air-filled interstices,which may have a thermal conductivity of 0.025 W/mC, compressiblesliding thermal interface 120 may improve heat transfer betweensubstrate 110 (e.g., as well as a printed circuit board and/or a digitalsignal processor of an electro-optic transceiver that includes substrate110) and riding heatsink 208. In some implementations, the thresholdthermal boundary resistance is less than approximately 1.5 square inchesKelvin per Watt (in²K/W). In some implementations, the thermal boundaryresistance is approximately 0.36 in²K/W. In this case, based ondecreasing the thermal boundary resistance from above 1.5 in²K/W to, forexample, 0.36 in²K/W, a pluggable optical module may be associated withan approximately 5 degrees Celsius (° C.) to 6° C. temperature reductionwhen operating with a 7 Watt (W) DSP.

As indicated above, FIGS. 2A-2D are provided merely as one or moreexamples. Other examples may differ from what is described with regardto FIGS. 2A-2D.

FIG. 3 is a flow chart of an example process 300 for using acompressible sliding thermal interface with a pluggable optical module.In some implementations, one or more process blocks of FIG. 3 may beperformed during assembly of an optical communications network.

As shown in FIG. 3, process 300 may include disposing a compressiblesliding thermal interface on a surface of an optical module (block 310).For example, the compressible sliding thermal interface may be depositedonto a depression in a substrate of the optical module. In someimplementations, the substrate of the optical module may be a housing ofthe optical module. In some implementations, the optical module may be apluggable optical module that is to contact a riding heatsink.

As further shown in FIG. 3, process 300 may include inserting theoptical module into a cage to dispose a riding heatsink in proximity tothe optical module and such that the cage applies a threshold clampingforce (block 320). For example, an opening of the cage may be sized toreceive the optical module, such that the optical module is clamped bythe opening of the cage. In some implementations, the optical module maycontact the riding heatsink. Additionally, or alternatively, the opticalmodule may be within a threshold proximity to the riding heatsinkwithout contacting the riding heatsink (e.g., with one or moreintermediate layers of material such as the compressible sliding thermalinterface, a layer of material of the cage, and/or the like). In thisway, based on the compressible sliding thermal interface extending abovea surface of the optical module, the compressible sliding thermalinterface increases a clamping force applied by the opening of the cage,thereby reducing a thermal boundary resistance and improving performanceof a riding heatsink of the cage. Moreover, the clamping force may causethe compressible sliding thermal interface to fill interstices between asurface of the optical module and a surface of the riding heatsink orthe cage, thereby reducing a thermal insulation relative to airinterstices of a metal-on-metal contact between the surfaces.

Process 300 may include additional implementations, such as any singleimplementation or any combination of implementations described herein.

Although FIG. 3 shows example blocks of process 300, in someimplementations, process 300 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 3. Additionally, or alternatively, two or more of theblocks of process 300 may be performed in parallel.

In this way, based on compressible sliding thermal interface 120protruding from a surface of substrate 110, a clamping force isincreased for a pluggable optical module, thereby reducing thermalcontact resistance between substrate 110 of the pluggable optical moduleand riding heatsink 208. Moreover, based on increasing the clampingforce and using a compressible, slidable material for compressiblesliding thermal interface 120, compressible sliding thermal interface120 fills interstices between respective surfaces of substrate 110 andriding heatsink 208, thereby decreasing thermal contact resistance.Based on decreasing thermal contact resistance, compressible slidingthermal interface improves heat transfer to riding heatsink 208, therebyimproving performance of riding heatsink 208 with respect to controllinga temperature of components of the pluggable optical module.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise forms disclosed. Modifications and variations may be made inlight of the above disclosure or may be acquired from practice of theimplementations.

Some implementations are described herein in connection with thresholds.As used herein, satisfying a threshold may, depending on the context,refer to a value being greater than the threshold, more than thethreshold, higher than the threshold, greater than or equal to thethreshold, less than the threshold, fewer than the threshold, lower thanthe threshold, less than or equal to the threshold, equal to thethreshold, or the like.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of various implementations includes each dependent claim incombination with every other claim in the claim set.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items(e.g., related items, unrelated items, a combination of related andunrelated items, etc.), and may be used interchangeably with “one ormore.” Where only one item is intended, the phrase “only one” or similarlanguage is used. Also, as used herein, the terms “has,” “have,”“having,” or the like are intended to be open-ended terms. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

What is claimed is:
 1. A device, comprising: a pluggable optical module,comprising: a substrate; and a compressible sliding thermal interfacematerial disposed on the substrate, wherein the compressible slidingthermal interface material is compressed by a threshold clamping forceto fill interstices between a first surface of the substrate and asecond surface of a riding heatsink, wherein the compressible slidingthermal interface protrudes from the first surface of the substrate suchthat insertion of the pluggable optical module into a cage that includesthe riding heatsink compresses the compressible sliding thermalinterface by the threshold clamping force to achieve a threshold thermalboundary resistance.
 2. The device of claim 1, wherein the compressiblesliding thermal interface material is a carbon nano-tube material. 3.The device of claim 1, wherein the compressible sliding thermalinterface material is a metal enclosure enclosing a conductive fluid. 4.The device of claim 1, wherein the compressible sliding thermalinterface material is applied to the substrate.
 5. The device of claim1, wherein the compressible sliding thermal interface material isapplied to the riding heatsink.
 6. The device of claim 1, wherein thethreshold thermal boundary resistance is between approximately 0.36square inches Kelvin per Watt (in²K/W) to 1.5 in²K/W.
 7. The device ofclaim 1, wherein the compressible sliding thermal interface material isassociated with a thermal conductivity of greater than 1000 Watts permeter Celsius (W/mC).
 8. A pluggable optical module, comprising: asubstrate, a compressible sliding thermal interface disposed on thesubstrate to contact a riding heatsink, wherein the compressible slidingthermal interface is compressed to fill interstices between a firstsurface of the substrate and a second surface of the riding heatsink,wherein the compressible sliding thermal interface protrudes from thefirst surface of the substrate such that insertion of the pluggableoptical module into a cage compresses the compressible sliding thermalinterface to achieve a threshold thermal boundary resistance between thepluggable optical module and the riding heatsink.
 9. The pluggableoptical module of claim 8, further comprising: a digital signalprocessor (DSP) disposed on the substrate, and wherein the compressiblesliding thermal interface is to transfer heat from the DSP to the ridingheatsink.
 10. The pluggable optical module of claim 8, wherein a fillfactor of interstices on a surface of the compressible sliding thermalinterface is greater than a threshold.
 11. The pluggable optical moduleof claim 8, wherein the compressible sliding thermal interfacecomprises: a flexible interface structure; and an interface fillingmaterial disposed inside the flexible interface structure.
 12. Thepluggable optical module of claim 11, wherein the interface fillingmaterial is a carbon fiber material or a carbon nano-tube material. 13.An electro-optic transceiver, comprising: a substrate for inserting intoa cage; and an interface material disposed on the substrate, wherein theinterface material is compressible to enable insertion of the substrateinto the cage, wherein the interface material extends above a surface ofthe substrate, wherein the interface material is thermally conductiveand is associated with a threshold thermal boundary resistance at athreshold clamping force.
 14. The electro-optic transceiver of claim 13,wherein the interface material is disposed over a portion of thesubstrate that is to align to a riding heatsink on insertion into thecage.
 15. The electro-optic transceiver of claim 14, wherein the ridingheatsink forms a section of the cage.
 16. The electro-optic transceiverof claim 13, wherein the substrate includes a depression of a depth ofbetween approximately 100 micrometers and 2000 micrometers to receivethe interface material.
 17. The electro-optic transceiver of claim 13,wherein a height of the interface material above the surface of thesubstrate is greater than 0 micrometers and less than approximately 2000micrometers.
 18. The electro-optic transceiver of claim 13, wherein aheight of the interface material above the surface of the substrate isless than 100 micrometers.
 19. The electro-optic transceiver of claim13, wherein a width of the interface material is between approximately 5millimeters (mm) and 50 mm.
 20. The electro-optic transceiver of claim13, wherein the electro-optic transceiver is pluggable.